At present, a known blistering machine M for producing blister packs, according to FIG. 1 (prior art) includes: a station 1, in which a first continuous band 2 of thermoformable material (e.g. PVC) is thermoformed to define a blister band with blisters 3 containing products 4, the blister band 2 being fed continuously along a determined feeding path A having a varying course; a station 5 for feeding products 4, having a unit for filling each blister 3 with a relevant product 4; a station 6 for feeding a second continuous band 7 (e.g. aluminium), feeding continuously the second continuous band 7 over the blister band 2 filled with the products 4; a station 8 for closing the first blister band 2 with the second band 7 by heat-sealing, in order to obtain a continuous blister pack band NB.
Downstream of the closing station 8, along the feeding path A with varying route, there is also a station 9, where the continuous blister pack band NB is stamped or punched, and a station 10, where the continuous blister pack band NB is pre-cut, to define pre-cut lines on the continuous blister pack band NB.
Afterwards, the continuous blister pack band NB with the pre-cut lines is divided, e.g. by cutting in a cutting station R, to define a plurality of single blister packs B.
Downstream of the cutting station R, the single blister packs B are withdrawn and fed to a boxing unit C, to be packaged in suitable boxes in known way.
Generally, the closing station 8 has two opposed rollers linked to each other, that is it includes a first, driving lower and recessed roller, that is having circumferential grooves 12a for housing blisters 3 with products 4, and a second roller 13, situated opposite and above the driving roller 12 and provided with heating means, to heat and pressure join the two bands 2 and 7, as they are placed one over the other.
As it can be seen in the machine M of FIG. 1, joining of the two bands, which results in the continuous blister pack band NB, occurs in a tangential line between the opposite rollers 12, 13, while an efficient grip while pulling the blister pack band NB is obtained due to the contact of the blister pack band NB along a wide arc defined on the peripheral surface of the driving roller 12a. The band NB is driven through a bending roller 11 and along an acute angle section of the feeding path A, downstream of the closing station 8 and defining a loop K.
The idler roller 11, defining the loop K and allowing best grip by the driving roller 12 on the band NB, can also oscillate between different working positions, in order to allow to make up for the continuous feeding of the band NB along the path A: this oscillation is necessary, because a continuous feeding of the bands 2 and 7, and consequently of the band NB must match with an operation of the stamping station 9 and the pre-cutting station 10, which in the known blistering machines, occurs in an intermittent way.